A comprehensive review on Covid-19 Omicron (B.1.1.529) variant

Abstract

The world has been combating different variants of SARS-COV-19 since its first outbreak in Wuhan city. SARS-COV-19 is caused by the coronavirus. The corona virus mutates and becomes more transmissible than earlier variants as the day passes. Till 24 November 2021, SARS-COV-19 has four variants Alpha, Beta, Gamma, and Delta, respectively. Among them, the delta variant caused severe havoc across the world. South Africa registered a new variant with the World Health Organization (WHO) on 24 November 2021, which is much more transmissible than previous variants. The WHO classified it as a variant of concern (VOC) on 26 November 2021 and called it the Greek letter Omicron (B.1.1.529), the fifteenth letter in the alphabet. Here a serious attempt was made to comprehend the omicron variant's origin, nomenclature, characteristics, mutations, the difference between delta and omicron variant, epidemiology, transmission, clinical features, impact on immunity, immune evasion, vaccines efficacy, etc.

Keywords: Clade; Lineage; Monoclonal antibodies(mAb); Omicron (B.1.1.529); Phylogeny; Receptor binding domain (RBD); Spike protein; Titers.

Fig. 1

Omicron global prevalence. Source of Fig. 1: Network for Genomic Surveillance in South Africa (NGS-SA). https://www.nicd.ac.za/wp-content/uploads/2022/01/Update-of-SA-sequencing-data-from-GISAID-14-Jan-2022_dash_v2-Read-Only.pdf.

Fig. 2

Omicron sub-lineage spike mutation profiles. Source of Fig. 2, 1) Lineage definitions based on https://github.com/cov-lineages/pango-designation/issues/367. 2) Images from https://covdb.stanford.edu/page/mutation-viewer/ (NICD SARS CoV 2 Sequencing Update 7 January 2022).

Fig. 3

Amino acid changes of omicron variant.

Fig. 4

(A and B) Spread of Omicron variant in south Africa. Figure source. MedComm, Volume. 2, Issue. 4, Pages. 838–845, First published. December/13/2021, DOI. (https://doi.org/10.1002/mco2.110) (He et al., 2021c). (C). Epidemiological data of Omicron variant in south Africa. Figure source; MedComm, Volume. 2, Issue. 4, Pages. 838–845, First published. December/13/2021, DOI. (https://doi.org/10.1002/mco2.110) (He et al., 2021c).

Fig. 4

(A and B) Spread of Omicron variant in south Africa. Figure source. MedComm, Volume. 2, Issue. 4, Pages. 838–845, First published. December/13/2021, DOI. (https://doi.org/10.1002/mco2.110) (He et al., 2021c). (C). Epidemiological data of Omicron variant in south Africa. Figure source; MedComm, Volume. 2, Issue. 4, Pages. 838–845, First published. December/13/2021, DOI. (https://doi.org/10.1002/mco2.110) (He et al., 2021c).

Fig. 5

The spike mutations of five worrisome variants are depicted in this graphic (VOCs). Figure source: Med Comm, Volume: 2, Issue: 4, Pages: 838–845, First published: 13 December 2021, (https://doi.org/10.1002/mco2.110).

Fig. 6

Protomer of the spike trimer is emphasized in green, its RBD in cyan, and the ACE2 receptor-bound is magenta (He et al., 2021c).Figure source: Med Comm, Volume: 2, Issue: 4, Pages: 838–845, First published: 13 December 2021, (https://doi.org/10.1002/mco2.110).

Fig. 7

Distribution of Omicron amino acid replacements on the three-dimensional SARS-CoV-2 Spike trimer. Figure source:https://virological.org/t/selection-analysis-identifies-significant-mutational-changes-in-omicron-that-are-likely-to-influence-both-antibody-neutralization-and-spike-function-part-1-of-2/771.

Fig. 8

An examination of variant spike mutations in (A) Delta and (B) Omicron (Kumar et al., 2021b). Figure source: Journal of Medical Virology, First published: 15 December 2021, (https://doi.org/10.1002/jmv.27526).

Fig. 9

At RBD, a study of (A) Delta and (B) Omicron variant mutations (RBD). Mutation is highlighted in orange. Omicron RBD possesses 15 mutations. However, Delta RBD has got only two (Kumar et al., 2021b).Figure source: Journal of Medical Virology, First published: 15 December 2021, (https://doi.org/10.1002/jmv.27526) (Kumar et al., 2021b).